Reporting as promised on our two night stay in later December (my first Accor stay after returning to Platinum status):
We arrived so early (shortly after 07:00) that I didn't even ask if a room was ready, just whether we could leave our luggage. We were taken up to the lounge and invited to help ourselves to coffee and/or breakfast. Our room was ready before 08:00 -- a Premier King (I had booked a standard queen). Everything, including the shower, worked as it should.
We enjoyed our stay and will probably return (the uncertainty simply reflects the impending addition of FRHI properties to the Accor options in Singapore).